The London School of Hygiene and Tropical Medicine (LSHTM), in collaboration with NIMR and KCMC, recently completed a research study on malaria prevention methods in the Muleba district of the Kagera region in northwestern Tanzania. They investigated whether high coverage of insecticide-treated bednets (ITNs) reduced the need for indoor residual spraying of insecticides (IRS). The research aimed to determine whether the use of ITNs alone is equally effective as the combined use of IRS plus ITNs. Results from the research will provide valuable information about malaria prevention strategies and the most efficient use of resources. This information can inform decisions, such as those made by the President's Malaria Initiative and National Malaria Control Programs, about whether IRS can be phased out without sacrificing malaria control.
The purpose of this research was to determine the impact of implementing both IRS and universal coverage of ITNs on malaria transmission in rural Tanzania. TRAction and its research partners aimed to answer the following questions:
Three post-intervention cross-sectional household surveys were undertaken in 2012. For each survey 80 households were randomly selected in the core area of each cluster. Households were eligible for the study if they had children aged 0.5-14 years. Any child aged 0.5-14 years was eligible to be included in the study. Up to three children per household were randomly selected for testing. Selected children were tested on the following day for malaria parasites using rapid diagnostic tests.
At baseline malaria prevalence, anaemia, ITN ownership, ITN usage and mean EIR per month were similar in the two study arms. After the intervention, the malaria prevalence was lower in the ITN+IRS arm than in the ITN only arm in all three surveys. Prevalence of moderate to severe anaemia in children under five years old was lower in the ITN+IRS arm in all post intervention surveys, but the difference was only statistically significant in survey B. Mean haemoglobin was lower in children under five years old in the ITN+IRS arm than in the ITN only arm in all three surveys. For all surveys, as per-protocol analysis showed statistically significant evidence for a protective effect of the combined intervention on malaria prevalence.
The results of this research were shared with local and national Ministry of Health partners as well as NGOs involved in malaria control. Additional dissemination events occurred at international public health conferences including the American Society for Tropical Medicine and Hygiene (ASTMH) conference.